Landlord had the same problem myself , asked how I pay the capital gains tax on the ETF's I sold , it's only a few k profit , I was told form 11 , registered for myaccount got a password after a week or so and form was so confusing , rang revenue and they weren't much help , so I'm just keeping the money , if they want it they can contact me. It's possible they fine me but meh. Probably be less than paying an accountant . I reckon 90% of time they will never chase you.